Field disturbance type motion detection system

ABSTRACT

A field disturbance proximity motion sensor apparatus includes a printed circuit board mounted in a plastic housing one-quarter wavelength from a metal backplate which serves as a reflector as well as providing antenna gain for a printed circuit half-wave dipole antenna fabricated on the printed circuit board. A single transistor oscillator/detector circuit is fabricated on the printed circuit board and forms a transceiver which is located adjacent to and coupled to the dipole antenna. Collector current change of the oscillator/detector transistor is sensed in response to any field disturbance whereupon an audio signal is produced which is amplified, filtered and fed to a comparator whose output activates an instrusion alarm device. All of the circuitry is mounted on the printed circuit board containing the antenna.

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United Amlung FIELD DISTURBANCE TYPE MOTION DETECTION SYSTEM [75]Inventor: Clifford L. Amlung, Nutley, NJ.

[73] Assignee: Security Devices Corporation,

- Pompton Lakes, NJ.

[22] Filed: Mar. 24, 1975 [21] Appl. No.: 561,229

[52] US. Cl 340/258 A; 325/19; 325/119;

343/795; 343/908 [51] Int. Cl. G08B 13/18 [58] Field of Search 340/258A, 258 B;

343/5 PD,"7.7, 100 AM, 818, 908, 702, 795; 325/19, 119, 352

[56] References Cited UNlTED STATES PATENTS 2,650,304 8/1953Schlesinger... 343/795 2,989,745 6/1961 Carroll 325/19 3,691,556 9/1972Bloice l l 340/258 A 3,806,941 4/1974 Cheal 340/258 A Dec. 9, 1975Primary ExaminerGlen R. Swann, Ill Attorney, Agent, or FirmBrady, OBoyle& Gates [57] ABSTRACT A field disturbance proximity motion sensorapparatus includes a printed circuit board mounted in a plastic housingone-quarter wavelength from a metal backplate which serves as areflector as well as providing 10 Claims, 5 Drawing Figures U.S. PatentDec. 9, 1975 Sheet 1 of3 3,925,774

FIG. 2

Sheet 2 of 3 3,925,774

U.S. Patent Dec. 9, 1975 FIG 3 U.S. Patent Dec. 9, 1975 Sheet 3 of33,925,774

SONIC ALARM FIELD DISTURBANCE TYPE MOTION DETECTION SYSTEM BACKGROUND OFTHE INVENTION 1. Field of the Invention The present invention isdirected generally to proximity or motion detection systems and moreparticularly to the class including field disturbance devices whichgenerate a directional antenna pattern around an area to be monitoredand accordingly generate a signal in response to any change in the fielddue to motion of an object or person in the area.

2. Description of the Prior Art Motion detection or intruder alarmsystems are well known in the art. Generally these systems may beclassified into two classes, one of which includes means which operateon the principle of the Doppler effect and the other includes meanswhich operate on the disturbed field principle.

Examples of Doppler type systems of which the applicant is aware aredisclosed in: U.S. Pat. 3,813,699, L. T. Saunders, May 28, 1974; U.S.Pat. 3,665,448, H. A. McGlinchey, et al., May 23, 1972; and U.S. Pat.3,376,507, A. H. McEuen, et al., Apr. 2, 1968. Examples of fielddisturbance type systems of which the applicant is aware is shown in:U.S. Pat. 3,839,709, K. Sugiura, Oct. 1, 1974; U.S. Pat. 3,747,012, R.Buck, July 17, 1973; and U.S. Pat. 3,483,437, J. J. Coyne, Dec. 9, 1969.

Additionally, such systems require some type of antenna as utilized incombination with electronic circuitry for radiating waves of radiofrequency energy through the space under surveillance. One such antennawhich is adapted to be utilized with electronic detection systems isdisclosed in U.S. Pat. 3,239,838, K. S. Kelleher, Mar. 8, 1966. Otherknown antenna structures are disclosed, for example, in U.S. Pat.2,990,574, J. R. McDougal, June 27, 1961; U.S. Pat. 2,724,772, D. E.Bridges et al., Nov. 22, 1955; U.S. Pat. 2,492,358, T. H. Clark, Dec.27, 1949; and finally U.S. Pat. 2,418,084, B. E. Montgomery, Mar. 25,1947.

SUMMARY Briefly, the subject invention is directed to an improved fielddisturbance type of proximity sensing system comprised of a printedcircuit half-wave dipole antenna coupled across the base-collectorjunction of a single transistor oscillator/detector which operates as atransceiver. Both the antenna and transceiver circuitry as well as abandpass filter-amplifier and comparator circuit are incorporated on aprinted circuit board which is mounted immediately behind the front faceof a plastic housing which has a metal backplate secured thereto aquarter wavelength away from the printed circuit board including theantenna. The base-collector connection of the transistor to the antennaresults in feedback through the antenna such that any change in theradiated field is detected as a change in the transistors collectorcurrent. A signal of audio frequency is thus provided and is fed to thebandpass filter-amplifier which provides a gain in the order of 2 X Theoutput of the amplifier is fed to one input of a comparator circuithaving a reference level signal applied to the other input. The outputof the comparator is coupled to an output transistor which operates as aDC switch to control the operation of a sonic alarm device or relaywhich is adapted to control other external circuitry.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspectivve view of theplastic housing for the subject invention, being partially cut away toillustrate the physical relationship of a printed circuit board locatedimmediately behind the front face thereof;

FIG. 2 is a central vertical cross-section of the arrangement shown inFIG. 1;

FIG. 3 is illustrative of the metallization layout fabricated on theprinted circuit board shown in FIGS. 1 and FIG. 4 is an electricalschematic diagram illustrative of the electrical power supply circuitryand voltage regulator located on the printed circuit board for poweringthe subject invention; and

FIG. 5 is an electrical schematic diagram illustrative of the preferredembodiment of the subject invention also located on the printed circuitboard.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings,and more particularly to FIGS. 1 and 2, reference numeral 10 denotes agenerally rectangular box-like housing made of plastic or the like, sothat radio frequency electromagnetic waves pass therethrough withoutappreciable attenuation. Immediately behind the front face 12 of thehousing 10, is affixed a substantially flat printed circuit board 14well known in the art, upon which is mounted the required electricalcircuit components, forming the subject invention. One of the componentscomprises a printed circuit half-wave dipole antenna 16 adapted foroperation in the UHF range and more particularly at a frequency of 915:SMHz (megaHertz). The antenna 16 is comprised of two generallytrapezoidal printed circuit elements (FIG. 1) l8 and 20 having a smallspacing therebetween. A printed circuit ladderlike structure 22 bridgesthe elements in the spacing for providing tuning i.e. feedback control.The printed circuit elements 18, 20 and 22 are fabricated in a commonplane on the front face 24 of the printed circuit board 14. A metalbackplate 26 is adapted to be fastened to the housing 10 such that it issubstantially parallel to the printed circuit board 14 containing theantenna 16, being separated therefrom by one-fourth wavelength. Themetal backplate 26 serves as a reflector for the antenna 16 forproviding a directional radiated antenna pattern as well as providing anantenna gain of 3db (decibels) when utilized in combination with thecircuitry to be described.

The antenna 16 is shown in greater detail in FIG. 3. The elements 18 and20 each have the same mean length (54A) and width W (for providing apredetermined antenna impedance) and are substantially identical withthe exception that element 20 additionally includes an appendage or tab28, at the lower edge which is closer to element 18 and which includesthe junction of the tuning structure 22. The element 20 also includes aninclined inner side portion 30 which diverges away from a like opposingside portion 32 of the element 18. Adjacent the tab 28 is a triangularshaped printed circuit land portion 34 which has an apex directed to thelower corner of the element 18 to which the tuning structure 22 isattached. The tab 28 and the land 34 are adapted to accommodate theconnection of the base and collector leads, respectively, of atransistor, not shown, at location 35 whose emitter is connected to theprinted circuit line element 36 so as to be positioned as closely aspossible to the antenna 16 for operation as a single transistoroscillator/detector circuit of a transceiver.

Adjacent the land 34 and the printed circuit element 36 is a relativelylarge encircling printed circuit area of metallization 38, which isadapted to act as a point of common reference potential, commonlyreferred to as ground. The location 40 of the printed circuit board 14is adapted to accommodate circuit means shown in FIG. 4 for providing asuitable DC power supply potential from a 115 volt AC line source. Thelocation 42, adjacent location 40, is adapted to accommodate solid statevoltage regulator means also shown in FIG. 4 for providing a regulatedDC supply potential +V at the metallization element 44 which element iscoupled to the inner metallization region 46 by means of ajumper lead48. The location 50 of the printed circuit board 14 is adapted toaccommodate solid state circuitry shown in FIG. by reference numeral 52for providing an active bandpass filter-amplifier combination and adifferential amplifier comparator circuit configured from an integratedcircuit module package having a plurality of operational amplifiersincluded therein. A typical example is identified as a 34-IOEmanufactured by RCA. The location 54 of the printed circuit board 14 isalso designed to accommodate a transistor switch, not shown, which isadapted to be coupled to an external sonic alarm device or other alarmcircuitry via a terminal land 56..

Referring now to the electrical circuitry embodying the subjectinvention, attention is directed to FIG. 4 which discloses the means forsupplying power for operating the circuitry shown in FIG. 5. A powertransformer 58 has its primary winding coupled to a 115 VAC power linewhile the secondary winding is connected to full-wave diode rectifier60, whose output is coupled to a voltage regulator 62. The voltageregulator typcially comprises an integrated circuit configuration suchas a CA 723 CE manufactured by RCA. The capacitors 64 and 66 act asfilter capacitors and a regulated DC power supply potential appears onprinted circuit lead 44 shown in FIG. 3. Such circuits are well known tothose skilled in the art.

Turning attention now to FIG. 5, it discloses, inter alia, a singleN-P-N transistor 68 which has its base, collector, and emitterrespectively connected to the metallization tab 28, metallization landportion 34 and printed circuit element 36. Since the base is connectedto the tab 28, it is directly connected to the M4 antenna element andone side of the ladder tuning structure 22 which bridges elements 18 and20. The base is also connected to a resistor 70 which is returned toground 38. The emitter is returned to ground 38 through an inductancecoil 72. The collector of transistor 68 is commonly connected to aresistor 74 and a capacitor 76 whose opposite ends are respectivelyconnected to the antenna elements 18 and 20 at the location of theconnection of the tuning structure 22 thereacross. Physically, theresistor 74 is connected between the metallization land portion 34 andthe tab 28, while the capacitor 76 is connected between the apex of theland portion 34 and the lower corner of the side portion 32 (FIG. 3)common to the tuning structure 22. A collector load resistor 78 havingthe +V supply potential applied via metallization region 46 is connectedto the collector of transistor 68 by means of the metallization land 34.

A bandpass filter/amplifier comprised of three operational amplifierportions 80, 82 and 84 of the integrated circuit module 52 is connectedto the collector of transistor 68. This is provided by means of resistor86 and capacitor 88 connected in series to the input of opera tionalamplifier 80. The positive power supply potential V+ on metallizationportion 46 (FIG. 3) is applied to the operational amplifier by means ofa resistor 90. A parallel combination of a capacitor 92 and resistor 94is coupled between the output and input of the operational amplifier 80to provide feedback required to partially implement a bandpass filtercharacteristic. The output of operational amplifier 80 is coupled to theinput of operational amplifier 82 by means of a resistor 96. Thepositive supply potential V+ is also applied to the operationalamplifier 82 by means of resistor 98. As in the case for the firstoperational amplifier 80, operational amplifier 82 also includes afeedback network comprised of the parallel combination of capacitor andresistor 102. The output of operational amplifier 82 is capacitivelycoupled to the third operational amplifier 84 by means of the seriescombination of capacitor 104 and resistor 106. The positive power supplypotential V-lis adapted to be coupled to the operational amplifier 84 bymeans of resistor 108. A single feedback element comprising resistor110, however, is connected between the input and output of operationalamplifier 84.

It is to be noted that the capacitance values of capacitors 92 and 100of the feedback networks for operational amplifiers 80 and 82 determinethe high frequency cut-off of the desired filter characteristic whereasthe capacitance values of the series coupling capacitors 88 and 104 atthe input of operational amplifier 80 and the input of operationalamplifier 84, determine the low frequency cut-off. The high frequencycut-offis selected to be in the order of l5Hz to prevent the 60l-Iz ACline frequency from affecting the opera tion of the subject inventionwhereas the low frequency cut-off is selected to be in the order of1.8Hz or lower and thus provides a bandpass for audio frequenciesappearing at the collector of transistor 68. The output of theoperational amplifier 84 is fed to one input of a fourth operationalamplifier portion 112 of the integrated circuit module 52 and isconfigured to operate as a comparator and more particularly adifferential amplifier. Accordingly, one input of operational amplifier112 is coupled to the output of operational amplifier 84 by means of theresistor 114. The other input of the operational amplifier 112 isconnected to a selectable DC reference voltage which is provided by apotentiometer 116 coupled between the positive supply potential V+ andground 38 and a fixed resistor 118 connected to the potentiometersslider element. The output of the differential amplifier comprised ofoperational amplifier 112 is connected to the base of a second N-P-Ntransistor 120 by means of a resistor which transistor comprises theswitch transistor referred to above located at location 54 on theprinted circuit board shown in FIG. 2. As shown in FIG. 5, the emitteris directly connected to the ground metallization 38, while thecollector is connected to the terminal 56 shown in FIG. 3. A sonic alarmdevice 122 or other desired device or circuitry is adapted to beconnected to terminal 56.

In operation, the transceiver circuit including the single transistor 68coupled to the antenna 16 is adapted to operate as an oscillator havinga frequency of operation in the UHF range and more particularly at afrequency of 915i SMHz. These oscillations are coupled to the dipoleelements 18 and 20 which in combination with the tuning structure 22 andthe metal backplate 26 positioned a one-fourth wavelength away from theantenna 16 generates a highly directional localized radiation patternwhich is transmitted to the area under surveillance. The coupling of thebase-collector junction of the transistor 68 across the antenna elements18 and 20, as shown in FIG. 5, provides a unique feedback through theantenna system under the control of the ladder structure 22 whereby anychange of the localized field results in a change in collector currentof the transistor 68, thus operating as the detector as well as theoscillator. Accordingly, any movement within the radiated field will bedetected as an audio signal of very low level at the collector oftransistor 68. The combination of the operational amplifier 80, 82, and84, and the circuitry associated therewith provides a bandpassfilter-amplifier having a gain in the order of2 X 10 which when comparedagainst a reference voltage set by potentiometer 116 for controllingsystem sensitivity, causes a DC output voltage from the comparatoramplifier 112 to turn the transistor 120 on if the reference level isexceeded and thereby drive any type of an appropriate alarm device.

In summation then, what has been shown and described is a singletransistor oscillator/detector forming a transceiver which is coupled toa single printed circuit half-wave dipole antenna mounted a quarterwavelength in front of a reflector formed of the back mounting plate ofthe plastic housing. The collector current change occurring as a resultof field disturbance of the highly directional antenna pattern issensed, amplified, filtered and fed to a comparator whose output isadapted to initiate an alarm.

Having thus described what is at present considered to be the preferredembodiment of the subject invention, I claim:

1. A field disturbance motion detection system generating anelectromagnetic wave pattern which is radiated to a selected locationand being responsive to a predetermined disturbance of said wave patternthereat to activate an alarm device, comprising in combination:

a housing having a front portion adapted to pass electromagnetic wavestherethrough without substantial attenuation;

a printed circuit board in said housing adjacently behind said frontportion;

said printed circuit board including thereon a single transceiverantenna comprised of a pair of opposing quarter wave antenna elementsincluding a spacing therebetween forming a half-wave dipole antenna, andtuning control means located in said spacing coupled between saidopposing elements;

an electromagnetic wave reflecting plate attached to said housingsubstantially one quarter wavelength behind said printed circuit boardthereby providing a predetermined antenna gain and directionalsensitivity;

a transceiver oscillator/detector circuit located immediately adjacentand coupled to said pair of antenna elements on said printed circuitboard and including a single transistor having an emitter, base andcollector, and additionally including a direct circuit connection ofsaid base to one of said pair of antenna elements, first circuit meanscoupling said base to a point of reference potential, second circuitmeans coupling said emitter to said point of reference potential, thirdcircuit means coupling said collector to said one antenna element,fourth circuit means coupling said collector to the other of said pairof antenna elements, and fifth circuit means coupling said collector toa supply potential, whereby said circuit is energized to provideoscillations which are coupled to said antenna whereupon electromagneticsignals of a predetermined frequency are radiated to a localized areawhich when a field disturbance occurs a change in collector current ofsaid transistor results providing a relatively low level output signalof another predetermined frequency across said fifth circuit means;

bandpass filter-amplifier means coupled to said collector and beingresponsive to said output signal occurring across said fifth circuitmeans and being adapted to increase the amplitude of said output signalby a predetermined gain;

comparator circuit means having first and second input meansrespectively coupled to the output of said bandpass filter-amplifiermeans and a reference potential whereby a control signal is generated inresponse to a field disturbance for initiating an alarm when theamplitude of said output signal from said bandpass amplifier exceedssaid reference potential.

2. The system as defined by claim 1 wherein said first, third and fifthcircuit means comprises means of a first type electrical impedance, saidfourth circuit means comprises means of a second type electricalimpedance and said second circuit means comprises means of a third typeelectrical impedance.

3. The system as defined by claim 2 wherein said first type ofelectrical impedance comprises resistive impedance means, said secondtype electrical impedance comprises capacitive type impedance means andsaid third type electrical impedance comprises inductance means.

4. The system as defined by claim 3 wherein said pair of opposingquarter wave antenna elements comprise printed circuit elements of agenerally trapezoidal configuration each having a pair of relativelylonger parallel sides of unequal length greater than a pair ofassociated non-parallel sides, and wherein the mutually opposing shorternon-parallel sides of said pair of elements diverge with respect to thelocation of said single transistor and wherein said tuning control meansis coupled between said mutually opposing shorter nonparallel sides.

5. The system as defined by claim 4 wherein said tuning control meanscomprises feedback control means in the form of a ladder type structureof printed circuit material.

6. The system as defined by claim 5 wherein said ladder type structureis comprised of a pair of parallely disposed printed circuit lineelements adjacent said mutually opposing non-parallel sides and aplurality of spaced apart printed circuit line elments interconnectingsaid pair of parallely disposed line elments.

7. The system as defined by claim 4 wherein the other non-parallelshorter side of said trapezoidal configuration is substantially at rightangles to the pair of parallel sides.

8. The system as defined by claim 7 wherein each of said pair of antennaelements have a predetermined width substantially less than the lengthof either of said parallel sides, said width providing a predeterminedanamplifier, said output circuit including a transistor having anemitter, base and collector and wherein said base is coupled to theoutput of said differential amplifier, said emitter is coupled to saidpoint of reference potential, and the collector is adapted to be coupledto said alarm device.

1. A field disturbance motion detection system generating anelectromagnetic wave pattern which is radiated to a selected locationand being responsive to a predetermined disturbance of said wave patternthereat to activate an alarm device, comprising in combination: ahousing having a front portion adapted to pass electromagnetic wavestherethrough without substantial attenuation; a printed circuit board insaid housing adjacently behind said front portion; said printed circuitboard including thereon a single transceiver antenna comprised of a pairof opposing quarter wave antenna elements including a spacingtherebetween forming a half-wave dipole antenna, and tuning controlmeans located in said spacing coupled between said opposing elements; anelectromagnetic wave reflecting plate attached to said housingsubstantially one quarter wavelength behind said printed circuit boardthereby providing a predetermined antenna gain and directionalsensitivity; a transceiver oscillator/detector circuit locatedimmediately adjacent and coupled to said pair of antenna elements onsaid printed circuit board and including a single transistor having anemitter, base and collector, and additionally including a direct circuitconnection of said base to one of said pair of antenna elements, firstcircuit means coupling said base to a point of reference potential,second circuit means coupling said emitter to said point of referencepotential, third circuit means coupling said collector to said oneantenna element, fourth circuit means coupling said collector to theother of said pair of antenna elements, and fifth circuit means couplingsaid collector to a supply potential, whereby said circuit is energizedto provide oscillations which are coupled to said antenna whereuponelectromagnetic signals of a predetermined frequency are radiated to alocalized area which when a field disturbance occurs a change incollector current of said transistor results providing a relatively lowlevel output signal of another predetermined frequency across said fifthcircuit means; bandpass filter-amplifier means coupled to said collectorand being responsive to said output signal occurring across said fifthcircuit means and being adapted to increase the amplitude of said outputsignal by a predetermined gain; comparator circuit means having firstand second input means respectively coupled to the output of saidbandpass filteramplifier means and A reference potential whereby acontrol signal is generated in response to a field disturbance forinitiating an alarm when the amplitude of said output signal from saidbandpass amplifier exceeds said reference potential.
 2. The system asdefined by claim 1 wherein said first, third and fifth circuit meanscomprises means of a first type electrical impedance, said fourthcircuit means comprises means of a second type electrical impedance andsaid second circuit means comprises means of a third type electricalimpedance.
 3. The system as defined by claim 2 wherein said first typeof electrical impedance comprises resistive impedance means, said secondtype electrical impedance comprises capacitive type impedance means andsaid third type electrical impedance comprises inductance means.
 4. Thesystem as defined by claim 3 wherein said pair of opposing quarter waveantenna elements comprise printed circuit elements of a generallytrapezoidal configuration each having a pair of relatively longerparallel sides of unequal length greater than a pair of associatednon-parallel sides, and wherein the mutually opposing shorternon-parallel sides of said pair of elements diverge with respect to thelocation of said single transistor and wherein said tuning control meansis coupled between said mutually opposing shorter non-parallel sides. 5.The system as defined by claim 4 wherein said tuning control meanscomprises feedback control means in the form of a ladder type structureof printed circuit material.
 6. The system as defined by claim 5 whereinsaid ladder type structure is comprised of a pair of parallely disposedprinted circuit line elements adjacent said mutually opposingnon-parallel sides and a plurality of spaced apart printed circuit lineelments interconnecting said pair of parallely disposed line elments. 7.The system as defined by claim 4 wherein the other non-parallel shorterside of said trapezoidal configuration is substantially at right anglesto the pair of parallel sides.
 8. The system as defined by claim 7wherein each of said pair of antenna elements have a predetermined widthsubstantially less than the length of either of said parallel sides,said width providing a predetermined antenna impedance.
 9. The system asdefined by claim 1 wherein said comparator circuit means comprises adifferential amplifier.
 10. The system as defined by claim 9 andadditionally including an output circuit adapted to activate said alarmdevice coupled to the output of said differential amplifier, said outputcircuit including a transistor having an emitter, base and collector andwherein said base is coupled to the output of said differentialamplifier, said emitter is coupled to said point of reference potential,and the collector is adapted to be coupled to said alarm device.